This invention generally relates to systems for identifying the kind and authenticity of printed matter such as currency notes.
With the recent spread of vending machines, money changers, band terminal machines etc., systems for examining and verifying the kind and authenticity of currency notes (band notes) such as one dollar notes, ten dollar notes, one hundred notes, etc. are becoming important.
Various systems for identifying different kinds of currency notes have hitherto been developed. For example, U.S. Pat. No. 4,179,685 discloses a system, which detects the edges of a currency note, extracts a binary pattern for a predetermined portion of the currency note beween the detected edges thereof, calculates the degree of coincidence between the extracted binary pattern and a standard binary pattern and determines the examined currency note to be a genuine note if a predetermined degree of coincidence is obtained between the two binary patterns.
Such a prior art currency note identifying system, however, has the following problems.
Many currency notes have such disfigurements as deviations of printing position, wrinkles and contaminations, and with such band notes great fluctuations of the binary pattern data result from the wrinkles and contaminations; sometimes the examined bank note is not identified as a genuine note due to wrinkles or contaminations causing excessive fluctuations of the binary pattern.
In order to cope with the deviations of the printing position of bank notes, it has been proposed to provide a deviation or skew detector and compare the detected pattern with a number of standard patterns provided for respective deviations or skew angles. Such a method of identification, however, requires a large scale and hence high price apparatus.